rarpd.c

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#ifndef lint
static  char    *sccsid = "@(#)rarpd.c	4.2  (ULTRIX)        10/16/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1989 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/


/* rarpd.c
 *
 *	This is the top level program for the RARP daemon.  
 *	NOTE:
 *		The rarpd doesn't recognize ARP packets sent
 *	to it. Such packets are ignored. The reason for such
 *	behaviour is: there should be no reason to send a ARP
 *	packet withing RARP as ARP is always available.
 *	
 *	HISTORY:
 *
 *	26-OCT-89 jsd
 *	Allow device to be optional (use pf0, ie. first network interface)
 *
 *	Created by : Uttam Shikarpur Nadig
 *	Date: 20th February 1989	
 *
 *	Usage: rarpd devicename	[-v] [-f filename]
 *		The device is specified as qe0, de0 etc.
 */


/* The standard stuff */

#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <sys/file.h>
#include <limits.h>
#include <strings.h>
#include <netdb.h>
#include <sys/socket.h>
#ifndef CTRACE	/* signal.h gives ctrace problems */
#include <signal.h>
#endif CTRACE
#include <sys/ioctl.h>
#include <syslog.h>
#include <sys/stat.h>
#include <nlist.h>

/* packet filter specific includes */

#include <net/pfilt.h>

/* Some definitions */

/* #define DEBUG 1		/* The debug option - prevents forking */ 
#define PACK_SIZE 1000 	 	/*buffer size to receive a rarp packet */
#define SEND_SIZE 100		/* The RARP packet being sent back */
#define MAX_LINE 256    	/* The length of the longest line allowable
			 	* in the file containing the mappings.
		  	 	*/
#define MAXHOSTLEN 256		/* The max. length of a host name */
#define READ_INTERVAL 6000	/* Time interval for reading "ether_file"
				 * -- in seconds
				 */
#define MSG_SIZE 1024		/* The maximum length of a syslog 
				 * message.
				 */
#define NONRARP	0		/* A NON RARP PACKET */

/* The packet type, for the filter. Everything at that
 * level is byte swapped */

#define F_RARP	  0x3580 	/* 0x8035 - RARP packet */
#define F_REQREVR 0x0300	/* 0x0003 - RARP request reverse type */

/* For user level interactions */
#define RARP   0x8035 


int verbose = 0;		/* The verbose flag; turned on
			  	 * by the -v flag
			  	 */
int debug = 0;			/* for debugging purpose ONLY */

typedef struct _mapper {
	u_char *ether;			/* The hardware address */
	u_char *ip;	 		/* The logical address */
	char   hostname[MAXHOSTLEN];	/* name of the host */
	struct _mapper *next;		/* Ptr to next struct. */
} mapper;

extern mapper *enet_list;
extern char *ether_file;	/* The mapping file */
extern char *progname;		/* The name of the program */
int valid_count;		/* # of correct entries in the /etc/ethers
				 * or the equivalent file
				 */

char device[64];		   /* The device on which the filter is
			 	    * operating. - qe0, ln0 etc. */
char *ether_file = "/etc/ethers";  /* The file for mapping ethernet
			 	    *  addr => internet
				    */
char *progname;			   /*  program name */
int disable = 0;		   /* disable re-reading the ethers file */
long time_mod;			   /* time when the ethers file was last
				    * modified
				    */
char *system = "/vmunix";	   /* The kernel image being used */

struct nlist nl[] = {
	{ "_Pfilt_read" },
	{ ""},
};
main (argc,argv)
int argc;
char **argv;

{
	char pack_buf[PACK_SIZE];	/* Buffer for the RARP packet */
	char send_buf[SEND_SIZE];	/* Buffer to send a resp. out */
	int pack_len;			/* Length of the pack. received */
	int fid;			/* The file descriptor */
	int res;			/* result of a call */
	int i;
	struct itimerval *value;	/* for timing puposes */
	struct itimerval *ovalue;	/* for timing puposes */
	void time_out(), read_mapping();
	char log_msg[MSG_SIZE];		/* message for syslog */
	int msg_len;			/* the message length */
	struct stat stat_val;		/* for stat'n "ether_file" */

	progname = argv[0];

	if (getuid()) {
		 fprintf (stderr, "%s: not super user\n", argv[0]);
		 exit(1);
	}

	openlog(progname, LOG_PID); /* opening syslog */

	syslog(LOG_INFO, "Started");

	/* Complete all the sanity-checks before forking 
		1) Check the command line.
		2) Check if packet filter has been installed.
		3) Check if the device is present.
		4) Check if the /etc/ethers file is present.
	*/
	parse_cmdline(argc,argv);  /* read the command line arguments */

	/* check if the packet filter has been configured */

	nlist (system, nl);
	if (nl[0].n_type == 0) {
		fprintf(stderr, "%s: cannot find symbol Pfilt_read in %s\n", progname, system);
		fprintf(stderr, "option PACKETFILTER does not appear to be configured in your kernel.\n");
		syslog(LOG_ERR, "Packet Filter is not configured in /vmunix");
		exit(1);
	}

	/* Check if the device is present */
	if (pfopen(device, 2) < 0) {
		syslog(LOG_ERR, "%m: %s", device);
		perror(device);
		exit(1);
	}
	close (device);


	/* stat the ether_file */
	if (stat(ether_file, &stat_val) < 0) {
		syslog(LOG_ERR, "%m\(%s\)", ether_file);
		perror(ether_file);
		usage();
	}

	time_mod = stat_val.st_mtime;

#ifndef DEBUG
	if (fork())
		exit(0);
	else {
		(void) open("/", O_RDONLY);
		(void) dup2(0, 1);
		(void) dup2(0, 2);
		{ int tt = open("/dev/tty", O_RDWR);
			if (tt > 0) {
				(void) ioctl(tt, TIOCNOTTY, 0);
				(void) close(tt);
			} else {
				syslog(LOG_WARNING, "%m: Cannot disassociate from controlling terminal");
			}
	       }
	}

#endif DEBUG

	/* Read in the mapping file */
	read_mapping();

	/* All the data required is now available
	 * in the list pointed to by the enet_list
	 * pointer.
	 * Time to activate the filter.
	 */

	fid = set_filter(device);	/* Set the filter */

	/* flush the queue before commencing */
	if (ioctl(fid, EIOCFLUSH, 0) < 0) 
		syslog(LOG_WARNING, "%m: could not flush input queue");

	/* set the timer, inorder to check the status of the
	 * "ether_file" periodicaly at period defined by
	 * READ_INTERVAL
	 */

	/* first allocate memory  for timers */
	if ((value=(struct itimerval *)malloc(sizeof(struct itimerval)))
						== NULL) {
		syslog(LOG_ERR, "%m: could not malloc value itimerval struct");
		exit(1);
	}

	if ((ovalue=(struct itimerval *)malloc(sizeof(struct itimerval)))
						== NULL){
		syslog(LOG_ERR, "%m: could not malloc ovalue itimerval struct");
		exit(1);
	}

	/* load the timer */
	value->it_value.tv_sec = READ_INTERVAL;
	value->it_value.tv_usec = 0;

	/* load the re-load field */
	value->it_interval.tv_sec = READ_INTERVAL;
	value->it_interval.tv_usec = 0;

	while(1) {
		if (!disable) {
			/* start the timer */
			setitimer (ITIMER_REAL, value, ovalue);
			/* enable the signal */
			(void) signal (SIGALRM, time_out);
		}
		pack_len = listen_4_rarp(fid, pack_buf, sizeof(pack_buf));
		if (debug)
			syslog(LOG_DEBUG, "received %d bytes; processing packet", pack_len);
		res = get_ip_addr(pack_buf, send_buf, fid ); /* Get the ip mapping */
		if ((res == NONRARP) && verbose) {
			/* a RARP packet was not received
			 * happens when filter screws up
			 */
			sprintf(log_msg, "Received packet from ->");
			msg_len = delimit(log_msg, 0, '>') + 1;
			for (i = 6; i < 12 ; i++, msg_len += 3)
				sprintf(log_msg + msg_len,"%.2x:", pack_buf[32+i] & 0xFF);
			continue;
		}
		if (res < 0) {
			sprintf(log_msg, "Not in %s file->", ether_file);
			/* search for the delimiter */
			msg_len = delimit(log_msg, 0, '>') + 1;
			for (i = 0; i < 6 ; i++,msg_len += 3)
				sprintf(log_msg + msg_len , "%.2x:", pack_buf[32+i] & 0xFF);
			/* log into syslog */
			syslog(LOG_ERR, "%s", log_msg);
			if (verbose) 
				syslog(LOG_ERR, "No response sent");
			continue;
		}
		if (verbose && res > 0 ) {
			sprintf(log_msg, "Received IP address request for ->");
			/* search for the delimiter */
			msg_len = delimit(log_msg, 0, '>') + 1;
			for (i = 0; i < 6 ; i++, msg_len += 3) 
				sprintf(log_msg + msg_len,"%.2x:", pack_buf[32+i] & 0xFF);
			syslog(LOG_INFO, "%s", log_msg);
		}
		if(verbose) {
			sprintf(log_msg,"The IP address is ->");
			/* search for the delimiter */
			msg_len = delimit(log_msg, 0, '>') + 1;
			for (i = 0; i < 4 ; i++) {
				sprintf(log_msg + msg_len, "%d.", send_buf[38+i] & 0xFF);
				msg_len = delimit(log_msg + msg_len, msg_len, '.') + 1;
			}
			syslog(LOG_INFO, "%s", log_msg);

			if (debug)
				syslog(LOG_DEBUG, "Going to send packet");
		}
		send_rarp_resp(fid, send_buf, res);	
	}
}


/**********************************************************************
 * Read the command line parameters. The options available
 * are: 
 *	-v		Verbose
 *	-f filename	The filename containing mappings
 *
 * The -v flag invokes the verbose mode of operation. The
 * -f option causes a file other than /etc/ethers to be
 * read inorder to gain knowledge of the ethernet to 
 * internet address mapping. Any
 * other option is ignored.
 *
 *********************************************************************/


parse_cmdline(argc,argv)
int argc;
char **argv;

{
	int i;
		
	/* Set up default network device */
	sprintf(device, "%s", "pf0");

	if (argc > 1) {	/* if more than 1 arg, check options */
		for (i=1; --argc>0; i++) {
			if (argv[i][0] != '-') {
			/* Ethernet interface given on command line */
				sprintf(device, "%s", argv[i]);
				continue;
			}

			switch (argv[i][1]) {
				case 'v':	/* turn verbose on */
					verbose = 1;
					break;

				case 'f':	/* the file to be read */
					ether_file = argv[i+1];
					i++;
					break;
				
				case 'n':	/* disable the timer */
					disable = 1;
					break;

				case 'D':	/* turn debug on */
					debug = 1;
					break;

				default:
					fprintf(stderr, "%s: unknown option, %s\n", progname, argv[i]);
					syslog(LOG_ERR, "unknown option, %s\n", argv[i]);
					usage();
				break;
			}
		}
  	}
}

/**********************************************************************
 * time_out is the interupt handler routine for SIGALRM
 *
 **********************************************************************/

void
time_out()
{
	struct stat stat_val;

	(void) signal (SIGALRM, SIG_IGN);

	/* First, go and stat the file in question */
	if (stat(ether_file, &stat_val) < 0) {
		syslog(LOG_ERR, "%m \(%s\)", ether_file);
		goto enable;
	}
	
	if (time_mod < stat_val.st_mtime) {
		read_mapping();
		if (debug || verbose) {
			syslog(LOG_INFO, "%s modified on %s",
				ether_file, ctime(&stat_val.st_mtime));
			syslog(LOG_INFO, "Re-read %s", ether_file);
		}
		time_mod = stat_val.st_mtime; /* update */
	}
	enable: (void) signal (SIGALRM, time_out);
}

usage()
{
	fprintf(stderr,"usage: %s [ device ] [-v] [-f filename] [-n]\n", progname);
	exit(1);
}


/************************************************************* 
 *	 
 *	These routines are used to parse the file containing 
 * 	the Ethernet to Internet address mappings. The routine
 *	"get_ip_addr" reads the list of mappings and fills in
 *	appropriate IP addr. for the machine.
 *
 *	The format of the file containing mappings should be:
 *
 *	ether_addr <space or tab(s)> hostname <anything else>
 *
 *	where,
 *
 *	ether_addr is of the form : "a:b:c:d:e:f"
 *	and hostname is of the form "myhost"
 *
 *	NOTE:
 *	a, b, c, d, e and f MUST be in HEXADECIMAL
 *
 *	A "#" in the FIRST column ONLY implies a comment follows and 
 *	anything from that till the end of the line is ignored.
 *	The parser checks ONLY the first 2 fields
 *	of a line and reads in the data.
 *
 *	eg.  8:0:2b:2:8b:0	hishostname	#This field is not parsed
 *	     8:0:2b:2:8c:1 	herhostname	# comment goes here
 *	     8:0:2b:2:8b:0	myhostname	  ... and here	
 *
 *	HISTORY:
 *
 *	Created by : Uttam Shikarpur Nadig
 *      Date: 22 February 1989
 *
 */

/****************************************************************